Field of the Invention
The present invention relates to a fuel cell system including an EGR (Exhaust Gas Recirculation) that circulates cathode-off gases.
Description of the Related Art
JP H8-500931 A discloses a technology of a cathode circulation system having an exhaust piping through which air-off gases (oxidant-off gases) flow to a cathode and a supply piping for supplying air (oxidant gases) connected together to the exhaust piping and causing the air-off gases in the exhaust piping to return to the supply piping to circulate a cathode-off gas in the system in order to discharge produced water remaining in the cathode of a fuel cell.
JP 2008-226591 A discloses a technology of reducing a stoichiometric amount of air (oxidant gases) to perform low-efficiency power generation in comparison with a normal operation, thereby promoting the warm-up.
When, however, JP H8-500931 A and JP 2008-226591 A are combined to immediately start the circulation of the oxidant-off gases when performing the low-efficiency power generation by reducing the stoichiometric amount of oxidant gases, there is a disadvantage that the amount of oxygen contained in the oxidant gases in the circulation system does not decrease, and it is difficult to quickly decrease a current/voltage characteristic (IV characteristic).
The present invention has been made to address the conventional disadvantage, and it is an object of the present invention to provide a fuel cell system that can quickly decrease a current/voltage characteristic.